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표준 영상에 의한 FFT 기반 상호상관 PIV 알고리즘의 불확도 해석
이석종(Sukjong Lee),최중근(Junggeun Choi),성재용(Jaeyoung Sung),황태규(Tae Gyu Hwang),도덕희(Deog Hee Doh) 한국가시화정보학회 2005 한국가시화정보학회지 Vol.3 No.2
Uncertainty introduced by a cross-correlation algorithm based on FFT has been investigated using PIV standard images. The standard images were generated by the Monte Carlo simulation method. Both bias and random errors from the velocity vector have been analyzed with regard to the particle diameter, displacement, and the number of particles. The uncertainty of velocity is evaluated based upon the ISO/IEC standard. As a result, a total error of 0.26% is included in the PIV cross-correlation algorithm. In addition, the uncertainty budget is presented, where the effect of the above three variables is examined. According to the budget, the variation of the number of particles within the interrogation window mainly contributes to the combined standard uncertainty of the real measured velocity field when excluding the effect of errors by the experiments itself. Finally, the expanded uncertainty is found to be about 12% at the 95% confidence level.
원심형 보조날개를 부착한 축류홴의 유동특성에 관한 실험적 연구
이석종(Sukjong Lee),성재용(Jaeyong Sung),이명호(Myeong-Ho Lee) 한국지열·수열에너지학회 2013 한국지열에너지학회논문집 Vol.9 No.3
A new type axial flow fan with centrifugal sub-blades has been designed and fabricated in the present study. We investigated velocity and pressure distributions in downstream flow fields of the fan experimentally to detect the detailed flow characteristics of new axial flow fan and an existing axial flow fan. Two-dimensional velocity components were probed by applying a particle image velocimetry system and pressure distributions were measured by Pitot tube and micro-manometer. Our results show that the velocity and pressure distributions at the flow fields of the new fan are quite different from the existing fan, and that the centrifugal sub-blades in the new fan can improve the performance characteristics in view of kinetic energy.
이석종(Sukjong Lee),성재용(Jaeyong Sung),이명호(Myeong Ho Lee) 한국생산제조학회 2013 한국생산제조학회지 Vol.22 No.1
In this paper, a high-speed imaging and an image processing technique have been applied to detect the position of a meniscus as a function of time in the micro capillary flows. Two fluids with low and high viscosities, ethylene glycol and glycerin, were dropped into the entrance well of a circular capillary tube. The filling times of the meniscus in both cases of ethylene glycol and glycerin were compared with the theoretical models - Washburn model and its modified model based on Newmans dynamic contact angle equation. To evaluate the model coefficients of Newmans dynamic contact angle, time-varying contact angles under the capillary flows were measured using an image processing technique. By considering the dynamic contact angle, the estimated filling time from the modified Washburn model agrees well with the experimental data. Especially, for the lower-viscosity fluid, the consideration of dynamic contact angle is more significant than for the higher-viscosity fluid.
성재용(Jaeyong Sung),이석종(Sukjong Lee),신평호(Pyung-ho Shin) 한국생산제조학회 2008 한국생산제조시스템학회 학술발표대회 논문집 Vol.2008 No.5
In this paper we describe an experimental method and an image processing technique for detecting the position of a meniscus in the micro capillary flows. The flow times of the meniscus in both cases of the ethylene glycol and glycerine were evaluated at the same temperature and position from the entrance of capillary tube. Physical properties of ethylene glycol and glycerine such as viscosity, surface tension, contact angle, which significantly impact on capillary force, were measured. As a result, it was found that a big change of viscosity and contact angle strongly influenced on the flow time inside the micro capillary tube.
초고층 공동주택에서 하이브리드 루프팬에 의한 입상덕트시스템의 환기성능평가
김재홍(Jae-Hong Kim),이석종(Sukjong Lee),성재용(Jaeyong Sung),이명호(Myeong Ho Lee) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
The ventilation performance of a vertical exhaust duct system in the high riser public house has been evaluated by a commercial software, Fluid Flow, which solves pressure losses through the duct system including bathroom fans and a hybrid roof fan. During the numerical experiments, outdoor wind condition and stack effects in summer and winter were considered as well as the operating conditions of a basement damper and the roof fan. The results show that the bathroom ventilation in summer is the most unsatisfactory. The opening of the basement damper has a problem that the polluted air in the lower floors is exhausted to the underground parking lot, not to the rooftop. If the basement damper is closed, the exhaust flow rate in the lower floors is not sufficient due to the strong flow resistance in the long vertical duct even though the roof fan is under operating.
신평호(Pyungho Shin),성재용(Jaeyong Sung),이석종(Sukjong Lee) 한국생산제조학회 2008 한국생산제조시스템학회 학술발표대회 논문집 Vol.2008 No.5
The present study focused on the characteristics of the droplet formation from an inkjet nozzle driven by a piezoelectric actuator. As an operating fluid, ethylene glycol was used and the physical properties of it such as viscosity, surface tension, contact angle and shear stress were measured. During the experiments, various temperatures and driving voltages imposed on a capillary tube are tested, which may result in a proper drive or a overdrive condition. In case of the proper drive condition, an image processing technique is applied to measure the diameter of a single free drop. As a result, the size of droplet is increased when the driving voltage is increased from 160 V to 190 V at 25℃. In the overdrive condition that temperature or driving voltage becomes higher than the proper drive condition, satellites and the misdirected jets happen.
신평호(Pyungho Shin),성재용(Jaeyong Sung),이석종(Sukjong Lee) 한국가시화정보학회 2008 한국가시화정보학회지 Vol.6 No.1
The present study has focused on the characteristics of droplet formation from an inkjet nozzle driven by a piezoelectric actuator. As an operating fluid, ethylene glycol was used and the physical properties of it such as viscosity, surface tension, contact angle and shear stress were measured. During the experiments, various temperatures and driving voltages are imposed on a capillary tube. These conditions result in a proper drive condition or an overdrive condition. In case of the proper drive condition, an image processing technique is applied to measure the diameter of a single free drop. As a result, the size of droplet is increased when the driving voltage is increased from 160 V to 190 V at 25℃. In the overdrive condition where temperature or driving voltage becomes higher than the proper drive condition, satellites and the misdirected jets happen.
성재용(Jaeyong Sung),도덕희(Deog Hee Doh),이석종(Sukjong Lee),황태규(Tae Gyu Hwang) 한국가시화정보학회 2006 한국가시화정보학회지 Vol.4 No.2
An experimental apparatus for PIV performance evaluation has been developed. Stardard uncertainty of a two-dimensional cross-correlation PIV system was investigated based upon the standard experimental apparatus, which was devised to model the rigid body rotating flows. For the systematic analysis of the uncertainty introduced by each component (algorithm, CCD camera, frame grabber) of the PIV system, standard images are fed into the component independently. The standard experiments show that 53% of the uncertainty in the present PIV system results from the frame grabber but the errors from the algorithm and digital camera are ignorable.